A friend of mine has a 91 nissan extra cab 2wd truck. 4 cylinder. He recently blew the motor and had another block installed using his original head. The mechanics who put the motor together as well as installing it told my friend to drive it home to see how it was. It backfired alot and when he got home the exhaust manifold was red hot. Obviously things are not right with it.
Could a timing issue cause red hot exhaust manifold or something else.
Thanks for any ideas.

my brother is building a hot-rod right now and had the same problem, seemed his head needed to be machined slightly because it was causing a gap where the intake ports match-up and it was sucking in air. too much air caused extremely hot exhaust due to very lean burning and heated up the manifold into the red. try taking it back and have them check the gasket and maybe have it machine ever so slightly.

In a word, yes, that could be a timing problem.

I don't know if it's as severe as this but the older Z24 would run with the timing chain off one sprocket. Maybe it's the same for that motor.